1. Field of the Invention
The present invention relates to a lens-fitted photographic film unit. More particularly the present invention relates to a lens-fitted photographic film unit in which, upon a single shutter release, plural exposures are simultaneously taken on a photographic film.
2. Description of the Prior Art
Known lens-fitted photographic film units (hereinafter referred to simply as film units) are disclosed U.S. Pat. Nos. 4,884,087 and 4,972,649, and are now on the market, e.g. under the trademark "Fujicolor Quick Snap" (manufactured by Fuji Photo Film Co., Ltd.). Such film units are a single-use camera pre-loaded with photograph filmstrip (hereinafter referred to as film). A user who has purchased the film unit winds the film frame by frame back into a cassette after each exposure. The film unit in its entirety is forwarded to a photographic laboratory after exposure of all the frames of the film.
The film unit is sold at a low price as compared with usual cameras. There have been a number of different variants of commercially available film units, such as a built-in flash type, a panoramic type, a telephotographic type, and a type changeable for close-up photography.
It is conceivable to design a film unit in which two taking lenses are mounted and are different as to focal length, and in which two exposures are simultaneously taken to create imaging frames on film, respectively in telephotographic and wide-angle fashions, upon a single operation of releasing a shutter device. A single shutter plate is also conceivable for the operation of opening or closing respective photographing systems associated with the telephoto and wide-angle lenses, and if it were possible to use such a shutter plate, this might be advantageous because of the low cost and simple processes for manufacturing the same.
Such single shutter plate would have two movable openings, each respectively associated with one of the photographing systems. The shutter speed, which is to say the exposure time, is equal for the two systems because the single shutter plate is moved at a speed common to both of the photographing systems. However, the lenses differ as to focal length and also as to f-number or aperture stop, when the associated stationary openings have a similar size. Should the shutter speed be determined to be suitable for one of the photographing systems, the shutter speed will be either too high or too low for the other photographing system. The common shutter speed will be too high for a high f-number, and so will cause an under-exposed condition of an imaging frame. Otherwise the common shutter speed will be too low for a low f-number, and will cause an over-exposed condition.